Fluorophosphates as Efficient Bifunctional Electrocatalysts for Metal–Air Batteries

An efficient bifunctional catalyst still remains a stupendous challenge for the use of energy storage devices such as rechargeable metal–air batteries and fuel cells as the current electrocatalysts are either oxygen reduction reaction (ORR) or oxygen evolution reaction (OER) selective and suffer from cost and stability issues. Co-phosphate-based bifunctional materials can be a plausible option owing to the enhanced stability imparted by the phosphate group. Inspired by the possibility, we report solution combustion synthesized porous Na2CoPO4F as a bifunctional electrocatalyst. Comparable to the existing conventional electrocatalysts, porous Na2CoPO4F exhibits robust bifunctional (ORR/OER) properties. Having F-based chemistry, the dissolution is minimal in an aqueous medium, paving a way for its use as a cathode for the aqueous rechargeable hybrid Na–air battery. Thus, based on the bifunctional catalytic performances and stability in an aqueous medium, this material can be envisaged as a cheap and an efficient catalyst for fuel cell as well as a cathode for metal–air batteries.